I feel my question is newbie, but I did not find the answer. Maybe my difficulties to reaf english fluently did not help !
I installed Signal, and then archived a conversation … Where is the file or the folder whis the archived conversation now ? (I should want to backup).

I Tried to find where Signal, and generaly Flatpacks apps are installed, hoping to find user’s file there, but even did not find that.

I don’t think it’s possible to export an archive. If you click your avatar in top left corner, there should be View archive options shown in the menu. Doesn’t look like there is anything more than this.

@barthalion I hope you are wright, tha archive is encrypted and there is no other way do open archives than signal’s View archive options …
But one of my concerns bout encrypted things is backup. How should I recover my stuff if I loose my (computer, hard disk …) it is on. I must have backup the encyption references (keys, luks headers …) and the encrypted stuff …
that’s my assle !
So, where is my archive ?
I did not reconize it in ~/.var/app/org.signal.Signal
It should be a question for Signal’s forum …